Thermoplastic compositions for halogenated elastomers

ABSTRACT

The invention provides a thermoplastic composition of C 4-C   7  isoolefin copolymers including halomethylstyrene derived units blended with a hindered amine or phosphine of the structure R 1  R 2  R 3  N or R 1  R 2  R 3  P wherein R 1 , R 2  and R 3  are preferably lower and higher alkyl groups. The resulting ionically associated, amino or phosphine modified elastomers are used to prepare thermoplastic elastomer blend compositions, including dynamically vulcanized compositions, containing more finely dispersed elastomers which results in compositions having improved mechanical properties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Application of InternationalApplication. No. PCT/US01/31370, filed Oct. 9, 2001, which is acontinuation of U.S. application Ser. No. 09/686,215, filed Oct. 11,2000, now U.S. Pat. No. 6,552,108 and the benefit of Provisionalapplication No. 60/296,698, filed Jun. 7, 2001, herein incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to halogenated elastomers having enhancedviscosity and thermoplastic elastomer composition containing theseelastomers. These thermoplastic elastomeric compositions comprise blendsof an isoolefin copolymer comprising at least a halomethylstyrenederived unit and at least one amine or phosphine.

BACKGROUND

A thermoplastic elastomer is generally defined as a polymer or blend ofpolymers that can be processed and recycled in the same way as aconventional thermoplastic materials, yet has properties and performancesimilar to that of vulcanized rubber at service temperatures. Blends oralloys of plastic and elastomeric rubber have become increasinglyimportant in the production of high performance thermoplasticelastomers, particularly for the replacement of thermoset rubber invarious applications.

Polymer blends which have a combination of both thermoplastic andelastic properties are generally obtained by combining a thermoplasticpolymer with an elastomeric composition in a way such that the elastomeris intimately and uniformly dispersed as a discrete particulate phasewithin a continuous phase of the thermoplastic. Early work withvulcanized compositions is found in U.S. Pat. No. 3,037,954 whichdiscloses static vulcanization as well as the technique of dynamicvulcanization wherein a vulcanizable elastomer is dispersed into aresinous thermoplastic polymer and the elastomer is cured whilecontinuously mixing and shearing the polymer blend. The resultingcomposition is a microgel dispersion of cured elastomer, such as butylrubber, chlorinated butyl rubber, polybutadiene or polyisoprene in anuncured matrix of thermoplastic polymer such as polypropylene.

Depending on the ultimate application, such thermoplastic elastomer(TPE) compositions may comprise one or a mixture of thermoplasticmaterials such as propylene homopolymers and propylene copolymers andlike thermoplastics used in combination with one or a mixture of curedor non-cured elastomers such as ethylene/propylene rubber, EPDM rubber,diolefin rubber, butyl rubber or similar elastomers. TPE compositionsmay also be prepared where the thermoplastic material used is anengineering resin having good high temperature properties, such as apolyamide or a polyester, used in combination with a cured or non-curedelastomer. Examples of such TPE compositions and methods of processingsuch compositions, including methods of dynamic vulcanization, may befound in U.S. Pat. Nos. 4,130,534, 4,130,535, 4,594,390, 5,021,500,5,177,147 and 5,290,886, as well as in WO 92/02582.

Particularly preferred elastomeric polymers useful for preparing TPEcompositions are halogenated random isoolefin copolymers comprising atleast halomethylstyrene derived units. Halogenated elastomericcopolymers of this type (referred to as BIMS polymers) and their methodof preparation are disclosed in U.S. Pat. No. 5,162,445. Curable TPEcompositions containing these copolymers are described in U.S. Pat. Nos.5,013,793 and 5,051,477, among others.

TPE compositions are normally prepared by melt mixing or melt processingthe thermoplastic and elastomeric components at temperatures in excessof 150° C. and under high shear mixing conditions (shear rate greaterthan 100 1/sec or sec⁻¹) in order to achieve a fine dispersion of onepolymer system within a matrix of the other polymer system. The finerthe dispersion, the better are the mechanical properties of the TPEproduct.

Due to the flow activation and shear thinning characteristic inherent insuch BIMS polymers, reductions in viscosity values of these polymers atincreased temperatures and shear rates encountered during mixing aremuch more pronounced than reductions in viscosity of the thermoplasticcomponent with which the BIMS polymer is blended. However, minimizationof the viscosity differential between the BIMS and thermoplasticcomponents during mixing and/or processing is essential for theprovision of uniform mixing and fine blend morphology that are criticalfor good blend mechanical properties.

SUMMARY OF THE INVENTION

The invention provides a composition, preferably a thermoplasticcomposition, comprising a halogenated elastomer and a viscosityenhancing agent such as a hindered amine or phosphine. In one embodimentof the invention, the halogenated elastomer is a C₄ to C₇ isomonoolefincopolymer comprising halomethylstyrene derived units. The copolymer ismixed with at least one hindered amine or phosphine compound having therespective structure (R₁ R₂ R₃)N or (R₁ R₂ R₃)P wherein R₁ is H or C₁ toC₆ alkyl, R₂ is C₁ to C₃₀ alkyl and R₃ is C₄ to C₃₀ alkyl and furtherwherein R₃ is a higher alkyl than R₁, said mixing being accomplished ata temperature above the melting point of said hindered amine orphosphine compound. The mixing is preferably done in such a manner tocreate a homogeneous blend.

The invention further provides a process for increasing the viscosity ofa C₄ to C₇ isomonoolefin copolymer comprising mixing the copolymer witha hindered amine or phosphine compound.

The invention provides a new approach towards viscosity enhancement ofBIMS copolymers such that their viscosity during high shear thermalmixing more closely approaches or matches the viscosity of thermoplasticmaterials with which they are blended, thereby facilitating more uniformmixing and the development of a finer dispersion of one polymer systemwithin the other matrix polymer system.

DETAILED DESCRIPTION

As used herein, the term “dynamic vulcanization” means a vulcanizationor curing process for a rubber contained in a thermoplastic elastomercomposition, wherein the rubber is vulcanized under conditions of highshear at a temperature above the melting point of the componentthermoplastic. The rubber is thus simultaneously crosslinked anddispersed as fine particles within the thermoplastic matrix, although asnoted above other morphologies may also exist.

As used herein, the term “vulcanized” means that the rubber component tobe vulcanized has been cured to a state in which the elastomericproperties of the crosslinked rubber are similar to those of the rubberin its conventional vulcanized state, apart from the thermoplasticelastomer composition. The degree of cure can be described in terms ofgel content or, conversely, extractable components. Alternatively thedegree of cure may be expressed in terms of crosslink density. All ofthese descriptions are well known in the art, for example in U.S. Pat.Nos. 5,100,947 and 5,157,081.

As used herein, the term “composition” includes blends of thehalogenation product of random copolymers of a C₄ to C₇ isomonoolefin,such as isobutylene, and an alkylstyrene comonomer, and the agent usedto influence the viscosity, such as an amine or phosphine. Thecomposition may also include other components.

As used herein, in reference to Periodic Table “Groups”, the newnumbering scheme for the Periodic Table Groups are used as in HAWLEY'SCONDENSED CHEMICAL DICTIONARY 852 (13th ed. 1997).

The term “elastomer”, as used herein, refers to any polymer orcomposition of polymers consistent with the ASTM D1566 definition. Theterm “elastomer” may be used interchangeably with the term “rubber”, asused herein.

Isoolefin Copolymer Comprising a Halomethylstyrene Derived Unit

Compositions of the present invention include at least one halogenatedelastomer. The halogenated elastomer in one embodiment of the inventionis a random copolymer of comprising at least C₄ to C₇ isoolefin derivedunits, such as isobutylene derived units, and halomethylstyrene derivedunits. The halomethylstyrene unit may be an ortho-, meta-, orpara-alkyl-substituted styrene unit. In one embodiment, thehalomethylstyrene derived unit is a p-halomethylstyrene containing atleast 80%, more preferably at least 90% by weight of the para-isomer.The “halo” group can be any halogen, desirably chlorine or bromine. Thehalogenated elastomer may also include functionalized interpolymerswherein at least some of the alkyl substituents groups present in thestyrene monomer units contain benzylic halogen or some other functionalgroup described further below. These interpolymers are herein referredto as “isoolefin copolymers comprising a halomethylstyrene derived unit”or simply “isoolefin copolymer”.

The isoolefin copolymer may also include other monomer derived units.The isoolefin of the copolymer may be a C₄ to C₁₂ compound, non-limitingexamples of which are compounds such as isobutylene, isobutene,2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 1-butene,2-butene, methyl vinyl ether, indene, vinyltrimethylsilane, hexene, and4-methyl-1-pentene. The copolymer may also further comprise multiolefinderived units. The multiolefin is a C₄ to C₁₄ multiolefin such asisoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, hexadiene, cyclopentadiene, and piperylene, andother monomers such as disclosed in EP 0 279 456 and U.S. Pat. Nos.5,506,316 and 5,162,425. Desirable styrenic monomer derived units thatmay comprise the copolymer include styrene, methylstyrene,chlorostyrene, methoxystyrene, indene and indene derivatives, andcombinations thereof.

In another embodiment of the invention, the interpolymer is a randomelastomeric copolymer of an ethylene derived unit or a C₃ to C₆ α-olefinderived unit and an halomethylstyrene derived unit, preferablyp-halomethylstyrene containing at least 80%, more preferably at least90% by weight of the para-isomer and also include functionalizedinterpolymers wherein at least some of the alkyl substituents groupspresent in the styrene monomer units contain benzylic halogen or someother functional group.

Preferred isoolefin copolymers may be characterized as interpolymerscontaining the following monomer units randomly spaced along the polymerchain:

wherein R and R¹ are independently hydrogen, lower alkyl, preferably C₁to C₇ alkyl and primary or secondary alkyl halides and X is a functionalgroup such as halogen. Desirable halogens are chlorine, bromine orcombinations thereof. Preferably R and R¹ are each hydrogen. The —CRR₁Hand —CRR₁X groups can be substituted on the styrene ring in either theortho, meta, or para positions, preferably para. Up to 60 mole % of thep-substituted styrene present in the interpolymer structure may be thefunctionalized structure (2) above in one embodiment, and in anotherembodiment from 0.1 to 5 mol %. In yet another embodiment, the amount offunctionalized structure (2) is from 0.4 to 1 mol %.

The functional group X may be halogen or some other functional groupwhich may be incorporated by nucleophilic substitution of benzylichalogen with other groups such as carboxylic acids; carboxy salts;carboxy esters, amides and imides; hydroxy; alkoxide; phenoxide;thiolate; thioether; xanthate; cyanide; cyanate; amino and mixturesthereof. These functionalized isomonoolefin copolymers, their method ofpreparation, methods of functionalization, and cure are moreparticularly disclosed in U.S. Pat. No. 5,162,445.

Most useful of such functionalized materials are elastomeric randominterpolymers of isobutylene and p-methylstyrene containing from 0.5 to20 mole % p-methylstyrene wherein up to 60 mole % of the methylsubstituent groups present on the benzyl ring contain a bromine orchlorine atom, preferably a bromine atom (p-bromomethylstyrene), as wellas acid or ester functionalized versions thereof wherein the halogenatom has been displaced by maleic anhydride or by acrylic or methacrylicacid functionality. These interpolymers are termed “halogenatedpoly(isobutylene-co-p-methylstyrene)” or “brominatedpoly(isobutylene-co-p-methylstyrene)”, and are commercially availableunder the name EXXPRO™ Elastomers (ExxonMobil Chemical Company, HoustonTex.). It is understood that the use of the terms “halogenated” or“brominated” are not limited to the method of halogenation of thecopolymer, but merely descriptive of the copolymer which comprises theisobutylene derived units, the p-methylstyrene derived units, and thep-halomethylstyrene derived units.

These functionalized polymers preferably have a substantiallyhomogeneous compositional distribution such that at least 95% by weightof the polymer has a p-alkylstyrene content within 10% of the averagep-alkylstyrene content of the polymer. More preferred polymers are alsocharacterized by a narrow molecular weight distribution (Mw/Mn) of lessthan 5, more preferably less than 2.5, a preferred viscosity averagemolecular weight in the range of from 200,000 up to 2,000,000 and apreferred number average molecular weight in the range of from 25,000 to750,000 as determined by gel permeation chromatography.

The copolymers may be prepared by a slurry polymerization of the monomermixture using a Lewis acid catalyst, followed by halogenation,preferably bromination, in solution in the presence of halogen and aradical initiator such as heat and/or light and/or a chemical initiatorand, optionally, followed by electrophilic substitution of bromine witha different functional derived unit.

Preferred halogenated poly(isobutylene-co-p-methylstyrene) arebrominated polymers which generally contain from 0.1 to 5 wt % ofbromomethyl groups. In yet another embodiment, the amount of bromomethylgroups is from 0.2 to 2.5 wt %. Expressed another way, preferredcopolymers contain from 0.05 up to 2.5 mole % of bromine, based on theweight of the polymer, more preferably from 0.1 to 1.25 mole % bromine,and are substantially free of ring halogen or halogen in the polymerbackbone chain. In one embodiment of the invention, the interpolymer isa copolymer of C₄ to C₇ isomonoolefin derived units, a p-methylstyrenederived units and a p-halomethylstyrene derived units, wherein thep-halomethylstyrene units are present in the interpolymer from 0.4 to 1mol % based on the interpolymer. In another embodiment, thep-halomethylstyrene is p-bromomethylstyrene. The Mooney Viscosity (1+8,125° C., ASTM D1646, modified) is from 30 to 60 MU.

Amine/phosphine Component

Viscosity enhancement of the BIMS copolymers is achieved by mixing theBIMS copolymer with the appropriate hindered amine or phosphinecompounds (or “viscosity enhancers”) under conditions of shear and attemperatures above the melting point of the amine or phosphine for aperiod of time sufficient to allow the amine or phosphine to becomeuniformly dispersed within the BIMS material, usually 1 to 10 minutesand at preferred temperatures in the range of 100 to 180° C.

Suitable preferred viscosity enhancers which may be used include thosedescribed by the formula (R₁ R₂ R₃)Q, wherein Q is a Group 15 element,preferably nitrogen or phosphorous, and wherein R₃ is a C₁₀ to C₂₀ alkyland R₁ and R₂ are the same or different lower alkyls, more preferably C₁to C₆ alkyls. Preferred are hindered amine/phosphine compounds which maybe used include those tertiary amines of the above formula (R₁ R₂ R₃)N.Especially preferred amines are decyldimethyl amine,hexadecyldimethylamine, hydrogenated tallowalkyl dimethyamine,dihydrogenated tallowalkylmethyl amine and like compounds.

Preferred hindered phosphine compounds of the formula (R₁ R₂ R₃)P arealso those wherein R₃ is C₁₀ to C₂₀ alkyl and R₁ and R₂ are the same ordifferent lower alkyls, more preferably C₁ to C₆ alkyls. Thesephosphines are analogous to the amines listed above.

The quantity of amine or phosphine incorporated into the BIMS copolymershould be sufficient such that the viscosity of the composition isenhanced (increased at a given shear rate and temperature). Theresultant composition may be referred to variously as the “amine orphosphine/copolymer” composition, or the “viscosity enhancer/copolymer”composition, or the “amine or phosphine/BIMS” composition. In oneembodiment, the viscosity value of the viscosity enhancer/BIMScomposition is greater than 1300 at 220° C. and 100 1/s shear rate, andin another embodiment the value is from 1300 to 6000 Pa·s at 220° C. and100 1/s shear rate, and from 1400 to 5000 Pa·s at 220° C. and 100 1/sshear rate in another embodiment. In another embodiment, the viscosityvalue of the viscosity enhancer/BIMS composition is greater than 200 at220° C. and 1000 1/s shear rate, and in another embodiment the value isfrom 200 to 600 Pa·s at 220° C. and 1000 1/s shear rate, and from 220 to550 Pa·s at 220° C. and 1000 1/s shear rate in another embodiment.Generally, from 0.05 to 2 mole equivalents, more preferably from 0.1 to1 mole equivalents, of amine or phosphine per halogen of BIMS issufficient.

The viscosity enhancer/BIMS composition, an amine/BIMS in oneembodiment, of the present invention is produced substantially in theabsence of a solvent. More particularly, the amine and BIMS componentsare blended by techniques known to those skilled in the art without theaddition of an organic solvent. Solvents, especially organic solvents,are substantially absent in the composition, or during blending of thecomponents. By “substantially absent”, it is meant that there is lessthan 5 wt % solvent by weight of the entire composition present, andless than 2 wt % in another embodiment.

The modified BIMS polymers of this invention are to be distinguishedfrom the ionomers disclosed in U.S. Pat. No. 5,162,445 or WO9410214. Thematerials produced in these references involve nucleophilic substitutionreactions conducted in organic solvent wherein benzylic halogen presentin the BIMS polymer is displaced thereby converting the polymer to anionomer with ionic amine or phosphine functionality. Materials producedin accordance with this invention are believed to be ionicallyassociated polymer chains with no halogen displacement in the polymerchains. This ionic association provides a modified polymer havingincreased viscosity as compared with the starting BIMS polymer.

Thermoplastic Polymers

The enhanced viscosity isoolefin copolymer of the invention is useful inblending with thermoplastics. Thermoplastic polymers suitable for use inthe present invention include amorphous, partially crystalline oressentially totally crystalline polymers selected from polyolefins,polyamides, polyimides, polyesters, polycarbonates, polysulfones,polylactones, polyacetals, acrylonitrile/butadiene/styrene copolymerresins, polyphenylene oxides, ethylene-carbon monoxide copolymers,polyphenylene sulfides, polystyrene, styrene/acrylonitrile copolymerresins, styrene/maleic anhydride copolymer resins, aromatic polyketonesand mixtures thereof. These and other thermoplastics are disclosed in,for example, U.S. Pat. No. 6,013,727.

Polyolefins suitable for use in the compositions of the inventioninclude thermoplastic, at least partially crystalline polyolefinhomopolymers and copolymers, including polymers prepared usingZiegler/Natta type catalysts or single sight catalysts such asmetallocene catalysts. They are desirably prepared from monoolefinmonomers having 2 to 6 carbon atoms, such as ethylene, propylene,1-butene, isobutylene, 1-pentene, copolymers containing these monomers,and the like, with propylene being the preferred monomer. As used in thespecification and claims, the term polypropylene includes homopolymersof propylene as well as reactor copolymers of propylene which cancontain 1 to 20 wt % of ethylene or an alpha-olefin comonomer of 4 to 16carbon atoms or mixtures thereof. The polypropylene can be highlycrystalline isotactic or syndiotactic polypropylene, usually having anarrow range of glass transition temperature (Tg). Commerciallyavailable polyolefins may be used in the practice of the invention.

The term “polypropylene” includes homopolymers of propylene as well asreactor copolymer of polypropylene which can contain from 1 to 20 wt %ethylene derived units or other 4 to 6 carbon α-olefin comonomer derivedunits. The polypropylene can be highly crystalline isotactic orsyndiotactic polypropylene. The reactor copolymer can be either randomor block copolymer. Other suitable thermoplastic polyolefin resinsinclude high density polyethylene (HDPE), low density polyethylene(LDPE), linear low density polyethylene (LLDPE), very low densitypolyethylene (VLDPE), ethylene copolymer resins, plastomeric copolymersof ethylene and 1-alkene, polybutene, and their mixtures.

Suitable thermoplastic polyamides (nylons) comprise crystalline orresinous, high molecular weight solid polymers including copolymers andterpolymers having recurring amide units within the polymer chain.Polyamides may be prepared by polymerization of one or more epsilonlactams such as caprolactam, pyrrolidinone, lauryllactam andaminoundecanoic lactam, or amino acid, or by condensation of dibasicacids and diamines. Both fiber-forming and molding grade nylons aresuitable. Examples of such polyamides are polycaprolactam (nylon-6),polylauryllactam (nylon- 12), polyhexamethyleneadipamide (nylon-6,6),polyhexamethyleneazelamide (nylon-6,9), polyhexamethylenesebacamide(nylon-6,10), polyhexamethyleneisophthalamide (nylon-6,IP) and thecondensation product of 11-amino-undecanoic acid (nylon-11).Commercially available thermoplastic polyamides may be advantageouslyused in the practice of this invention, with linear crystallinepolyamides having a softening point or melting point between 160°C.-230° C. being preferred.

Suitable thermoplastic polyesters which may be employed include thepolymer reaction products of one or a mixture of aliphatic or aromaticpolycarboxylic acids esters of anhydrides and one or a mixture of diols.Examples of satisfactory polyesters includepoly(trans-1,4-cyclohexylene), poly(C₂ to C₆ alkane biscarboxylates)such as poly(trans-1,4-cyclohexylene succinate) andpoly(trans-1,4-cyclohexylene adipate); poly(cis- ortrans-1,4-cyclohexanedimethylene) alkanedicarboxylates such aspoly(cis-1,4-cyclohexane-di-methylene) oxlate andpoly(cis-1,4-cyclohexane-di-methylene) succinate, poly(C₂ to C₄ alkyleneterephthalates) such as polyethylene terephthalate andpolytetramethylene-terephthalate, poly(C₂ to C₄ alkylene isophthalates)such as polyethyleneisophthalate and polytetramethylene-isophthalate andlike materials. Preferred polyester are derived from aromaticdicarboxylic acids such as naphthalenic or ophthalmic acids and C₂ to C₄diols, such as polyethylene terephthalate and polybutyleneterephthalate. Preferred polyesters will have a melting point in therange of 160° C. to 260° C.

Poly(phenylene ether) (PPE) thermoplastic engineering resins which maybe used in accordance with this invention are well known, commerciallyavailable materials produced by the oxidative coupling polymerization ofalkyl substituted phenols. They are generally linear polymers having aglass transition temperature in the range of 190° C. to 235° C. Examplesof preferred PPE polymers include poly(2,6-dialkyl-1,4-phenylene ethers)such as poly(2,6-dimethyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dipropyl-1,4-phenylene ether) andpoly(2-ethyl-6-propyl-1,4-phenylene ether). These polymers, their methodof preparation and blends with polystyrene are further described in U.S.Pat. No. 3,383,435.

Other thermoplastic resins which may be used include the polycarbonateanalogs of the polyesters described above such as segmented poly(etherco-phthalates); polycaprolactone polymers; styrene resins such ascopolymers of styrene with less than 50 mole % of acrylonitrile (SAN)and resinous copolymers of styrene, acrylonitrile and butadiene (ABS);sulfone polymers such as polyphenyl sulfone and like engineering resinsas are known in the art.

Additives

The compositions of the invention may include plasticizers, curativesand may also include reinforcing and non-reinforcing fillers,antioxidants, stabilizers, rubber processing oil, plasticizers, extenderoils, lubricants, antiblocking agents, anti-static agents, waxes,foaming agents, pigments, flame retardants and other processing aidsknown in the rubber compounding art. Such additives can comprise up to50 wt % of the total composition. Fillers and extenders which can beutilized include conventional inorganics such as calcium carbonate,clays, silica, talc, titanium dioxide, carbon black and the like. Therubber processing oils generally are paraffinic, naphthenic or aromaticoils derived from petroleum fractions, but are preferably paraffinic.The type will be that ordinarily used in conjunction with the specificrubber or rubbers present in the composition, and the quantity based onthe total rubber content may range from zero up to 1-200 parts by weightper hundred rubber (phr). Plasticizers such as trimellitate esters mayalso be present in the composition.

Moreover, various phenolic resins known to the art and to the literaturecan be utilized, as well as various phenol-formaldehyde resins as setforth in “The Chemistry of Phenol-Formaldehyde Resin Vulcanization ofEPDM: Part I. Evidence for Methylene Crosslinks,” by Martin Van Duin andAniko Souphanthong, 68 RUBBER CHEMISTRY AND TECHNOLOGY 717-727 (1995).

The cure agent of the present invention may include any number ofcomponents such as a metal or metal ligand complex, accelerators, resinsor other components known in the art to affect a cure of an elastomer.In its broadest embodiment, the cure agent is at least a Group 2-14metal oxide or metal ligand complex, wherein at least one ligand is ableto undergo a substitution reaction with the inducer compound. In oneembodiment, the at least one cure agent is a metal oxide which includeszinc oxide, hydrated lime, magnesium oxide, alkali carbonates, andhydroxides. In particular, the following metal-based cure agents arecommon curatives that will function in the present invention: ZnO, CaO,MgO, Al₂O₃, CrO₃, FeO, Fe₂O₃, and NiO, and/or carboxylates of thesemetals. These metal oxides can be used in conjunction with thecorresponding metal carboxylate complex, or with the carboxylate ligand,and either a sulfur compound or an alkylperoxide compound. (See also,Formulation Design and Curing Characteristics of NBR Mixes for Seals,RUBBER WORLD 25-30 (1993).

These metal oxides can be used in combination with another compound suchas a fatty acid, and the cure agent is not herein limited to the metaloxide or metal ligand complex alone. Examples of organic or fatty acidsthat can be used in the invention are stearic, oleic, lauric, palmitic,myristic acids, and mixtures thereof, and hydrogenated oils from palm,castor, fish, and linseed oils. The use of these cure agents isdiscussed in RUBBER TECHNOLOGY 20-58 (Maurice Mortin, ed., Chapman &Hall 1995), and in Rubber World Magazine's BLUE BOOK 2001 109-137 (DonR. Smith, ed., Lippincott & Peto, Inc. 2001); and U.S. Pat. No.5,332,787.

The amount of the curing agent will generally vary depending upon thetype utilized and especially the desired degree of cure, as is wellrecognized in the art. For example, the amount of sulfur is generallyfrom 1 to 5, and preferably from 2 to 3 parts by weight per 100 parts byweight of the composition. The amount of the peroxide curing agent isgenerally from 0.1 to 2.0 parts by weight, the amount of the phenoliccuring resin is generally from 2 to 10 parts by weight, and the amountof the hindered amine is from 0.1 to 2 parts by weight, all based upon100 parts by weight of the composition.

In one embodiment of the invention, curatives may be present from 0.5 to20 phr of the composition, and from 1 to 10 phr in another embodiment.In another embodiment, curatives are substantially absent from thecomposition. By “substantially absent”, it is meant that traditionalcuratives such as phenolic resins, sulfur, peroxides, metals and metaloxides, and metal-ligand complexes are not present in the composition.

Processing

The BIMS component of the thermoplastic elastomer is generally presentas small, i.e., micro-size, particles within a continuous plasticmatrix, although a co-continuous morphology or a phase inversion is alsopossible depending on the amount of rubber relative to plastic, and thecure system or degree of cure of the rubber. The rubber is desirably atleast partially crosslinked, and preferably is completely or fullycross-linked in the final vulcanized thermoplastic composition. Thepartial or complete crosslinking can be achieved by adding anappropriate rubber curative to the blend of thermoplastic polymer andrubber and vulcanizing the rubber to the desired degree underconventional vulcanizing conditions. However, it is preferred that therubber be crosslinked by the process of dynamic vulcanization.

Dynamic vulcanization is effected by mixing the thermoplastic elastomercomponents at elevated temperature in conventional mixing equipment suchas roll mills, Banbury™ mixers, Brabender™ mixers, continuous mixers,mixing extruders and the like. The unique characteristic of dynamicallycured compositions is that, notwithstanding the fact that the rubbercomponent is partially or fully cured, the compositions can be processedand reprocessed by conventional plastic processing techniques such asextrusion, injection molding, blow molding and compression molding.Scrap or flashing can be salvaged and reprocessed.

Those ordinarily skilled in the art will appreciate the appropriatequantities, types of cure systems and vulcanization conditions requiredto carry out the vulcanization of the BIMS rubber. The rubber can bevulcanized using varying amounts of curative, varying temperatures andvarying time of cure in order to obtain the optimum crosslinkingdesired. Any known cure system for the rubber can be used, so long as itis suitable under the vulcanization conditions with the specific BIMSrubber being used and with the thermoplastic component. These curativesinclude sulfur, sulfur donors, metal oxides, resin systems,peroxide-based systems, hydrosilation curatives, containing platinum orperoxide catalysts, and the like, both with and without accelerators andco-agents. Such cure systems are well known in the art and literature ofvulcanization of elastomers.

Depending upon the desired applications, the amount of rubber present inthe composition may range from 10 to 90 wt % of the total polymercontent of the composition. In most applications and particularly wherethe rubber component is dynamically vulcanized, the rubber componentwill constitute less than 70 wt %, more preferably less than 50 wt %,and most preferably 10-40 wt % of the total polymer content of thecomposition.

Melt processing temperatures of the TPE compositions will generallyrange from above the melting point of the highest melting polymerpresent in the TPE composition up to 300° C. Preferred processingtemperatures will range from 140° C. up to 260° C., from 150° C. up to240° C. in another embodiment, and from 170° C. to 220° C. in yetanother embodiment.

The hindered amine or phosphine compound may be combined with the BIMSrubber component at any mixing stage, i.e., when the BIMS andthermoplastic polymer are initially mixed or at the time that curativesor other additives are mixed where dynamically vulcanized compositionsare prepared. However, in a preferred embodiment, the hindered amine orphosphine material is fist compounded the BIMS polymer at temperaturesup to 300° C. to provide a modified BIMS polymer of increased viscosity,and this modified polymer then blended with the thermoplastic resin andany other additives present in the TPE composition.

The thermoplastic composition of the invention results from the mixingof the amine or phosphine, the isoolefin copolymer, and thethermoplastic, in any order. In one embodiment, the copolymer is firstmixed with the amine or phosphine to form an amine orphosphine/copolymer composition, followed by mixing with thethermoplastic. In another embodiment, the three components are mixedsimultaneously. Further, the thermoplastic composition in one embodimentof the present invention is produced substantially in the absence of asolvent. More particularly, the amine and BIMS components are blended bytechniques known to those skilled in the art without the addition of anorganic solvent. Further, the amine or phosphine/copolymer compositionthus formed may be mixed with the thermoplastic in the absence of asolvent. Solvents, especially organic solvents such as hexane, methylenechloride and other solvents known to dissolve polyolefins, nylons andhalogenated elastomers, are substantially absent in the composition, orduring blending of the components. By “substantially absent”, it ismeant that there is less than 5 wt % solvent by weight of the entirecomposition present.

The thermoplastic compositions of the invention may comprise from 10 to90 wt % of the thermoplastic and from 90 to 10 wt % of the isoolefincopolymer. In another embodiment, the thermoplastic compositions of theinvention may comprise from 20 to 80 wt % of the thermoplastic and from80 to 20 wt % of the isoolefin copolymer. In another embodiment, thethermoplastic compositions of the invention comprise from 40 to 60 wt %of the thermoplastic, and from 60 to 40 wt % of the isoolefin copolymer.The vulcanized thermoplastic compositions have a tensile toughness ofgreater than 1000 psi in one embodiment, and greater than 2000 psi inanother embodiment (ASTM D1708 as in text below). The vulcanizedthermoplastic compositions have a strain at break value of greater than200% in one embodiment, and greater than 300% in another embodiment(ASTM D1708 as in text below).

EXAMPLES

The following examples are illustrative of the invention. Materials usedin the examples are shown in Table 1.

Example 1

This example illustrates the breakdown in viscosity of brominatedpoly(isobutylene-co-p-methylstyrene) (identified as BIMS 1, 2 and 3 inTable 1). Samples of each rubber were subjected to shear rates from 50to 5,000 s⁻¹ using a capillary rheometer at a temperature of 220° C.Viscosity data were subsequently corrected for entry pressure andnon-Newtonian flow profile. Only viscosity values at 100, 500, 1000 and1500 s⁻¹ are shown for comparison. Table 2 shows the drop off ofviscosity as a function of increased rate of shear for each of theserubbers.

Example 2

All tertiary amines, DM16D, DMHTD and M2HT, were blended into BIMS 2 bya Brabender™ mixer running at 150° C. and at 60 rpm. Amine amounts wereadded in mole equivalents to the bromine content in BIMS. As shown inTable 3, by adding DM16D, viscosity values at all shear rates of BIMS at220° C. could be raised.

The presence of tertiary amine of DM16D in BIMS does not lead to anythermal degradation in BIMS as demonstrated in Table 4. Viscosity valuesof DM16D-added BIMS at each temperature remain relatively unchangedduring thermal cycling between 100 and 250° C.

The enhancement in viscosity value in tertiary-amine modified BIMSdepends on the amine structure. By comparing the data in Table 5 withTable 3, hexadecyl-dimethylamine of DM16D provides more enhancement inviscosity as compared with that of DMHTD, which is dimethyl but withpredominately C₁₈ R₃ group as compared with the C₁₆ R₃ group for DM16D.When M2HT, which is dihydrogenated tallowalkyl-methylamine and has bothR₂ and R₃ groups as the alkyl group with predominantly C₁₈, is applied(see Table 6), the viscosity enhancement becomes less significant ascompared with that provided by adding DM16D.

Example 3

A blend comprising 60 wt % of MFR 1.5 polypropylene (ExxonMobil PP4292)and 40 wt % of BIMS 2 modified with 0.5 mol equivalents of DM16D wasprepared by mixing the components using a Brabender™ mixer at 80 RPM and220° C. for a period of 5 minutes.

An otherwise identical control blend was prepared except the BIMS 2 wasnot amine modified (control). Morphologies of the resulting blends wereexamined by AFM (Atomic Force Microscopy) followed by image processingto determine dispersion sizes in terms of number average equivalentdiameter. All specimens were analyzed within 8 hours after cryofacing toprevent specimen relaxation. During cryofacing, the specimens werecooled to −150° C. and cut with diamond knives in a Reichert cryogenicmicrotome. They were then stored in a dissector under flowing drynitrogen gas to warm up to ambient temperatures without condensationbeing formed. Finally, the faced specimens were mounted in a miniaturesteel vice for AFM analysis. The AFM measurements were performed in airon a NanoScope Dimension 3000 scanning probe microscope (DigitalInstrument) using a rectangular Si cantilever. AFM phase images of allspecimens were converted into a TIFF format and processed usingPHOTOSHOP™ (Adobe Systems, Inc.). The image processing tool kit(Reindeer Games, Inc.) was applied for image measurements. Results ofimage measurements were written into a text file for subsequent dataprocessing using EXCEL™. Results are shown in Table 7. These resultsdemonstrate a nearly 30% reduction in size of the dispersed BIMS rubbercompared with the control.

In the following examples, additional thermoplastic blends, or ionicallylinked alloy (ILA) compositions were prepared containing varying levelsof tertiary amine and their mechanical properties were evaluated vs.control samples which contain no tertiary amine additive. Thethermoplastic polymer used in these blends is polypropylene (PP) PP4722,a 2.8 MFR polypropylene available from ExxonMobil Chemical Co.

Example 4

The tertiary amine was diluted with a paraffinic mineral oil when addedto the blend of thermoplastic and elastomer. Blends of PP/BIMS wereprepared by mixing them in a Brabender mixer at a temperature of 190° C.and a rotor speed of 60 rpm. The PP pellets were first melted in thepresence of a suitable stabilizer such as Irganox 1076. The elastomerfollowed by the oil-diluted Armeen DM16D was subsequently added. At theend, a metal oxide, e.g., MgO, was also added in the blend to act as anacid acceptor. Several ILA compositions with a thermoplastic/elastomerblend ratio of 40/60 are shown in Table 8 (numbers expressed in parts byweight). For inventive composition (b), an exact stoichiometric match inthe bromine and amine groups was adopted, while in inventivecompositions (a) and (c) more and less amine than bromine groups,respectively, are present.

Each ILA composition of Table 8 was compression-molded at 190° for 15minutes to make pads of thickness about 0.08 inch. Tensile stress-strainmeasurements were performed on these molded pads (stored under ambientconditions for 48 hours prior to tests). Micro-dumbbell specimens (ASTMD1708) were used (test temperature 25° C.; Instron cross-head speed 2inch/min). As shown in Table 8 the incorporation of ionic associationsin the PP/BIMS/oil blends (inventive examples (a) to (c) containing 10phr oil). increases the strain at break, the maximum stress near thebreak point, and the tensile toughness (defined as the area under thestress-strain curve) significantly compared to the control example.

Example 5

Other ILA compositions with a thermoplastic/elastomer blend ratio of30/70 are shown in Table 9 (numbers expressed in parts by weight). Forinventive compositions (d) and (e) with 10 phr and 20 phr oilrespectively, an exact stoichiometric match in the bromine and aminegroups was adopted. Here, again it can be noted that incorporation ofionic associations in the PP/BIMS/oil blend (10 phr or 20 phr oil)increases the strain at break, the maximum stress near the break point,and the tensile toughness significantly compared to the controls.

In Table 10, ILA compositions with a thermoplastic/elastomer blend ratioof 30/70 using the higher Mooney BIMS are shown. In this series the oillevel is also varied. For inventive compositions (f), (g) and (h), anexact stoichiometric match in the bromine and amine groups was adopted.The results indicate that the incorporation of ionic associations in thePP/BIMS/oil blend (10, 20 or 30 phr oil) increases the maximum stressnear the break point and the tensile toughness over the controlexamples. At higher oil levels, the strain at break of the blend withoutionic associations is higher than the corresponding blend with ionicassociations perhaps due to the higher molecular weight of BIMS 2.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

All priority documents are herein fully incorporated by reference forall jurisdictions in which such incorporation is permitted. Further, alldocuments cited herein, including testing procedures, are herein fullyincorporated by reference for all jurisdictions in which suchincorporation is permitted.

TABLE 1 Materials Used Designation Description Material BIMS 1 BIMSrubber, Mooney EXXPRO ™ 89-1 viscosity of 35 units, *0.75 ExxonMobilChemical mol % Br, 5 wt % PMS BIMS 2 BIMS rubber, Mooney EXXPRO ™ 89-4,viscosity of 45 units, *0.75 ExxonMobil Chemical mol % Br, 5 wt % PMSBIMS 3 BIMS rubber, Mooney EXXPRO ™ 91-11, viscosity of 65 units, *1.1ExxonMobil Chemical mol % Br, 5 wt % PMS DM16D Tertiary amine,hexadecyl- Armeen DM16D, Akzo dimethylamine Nobel Chemical DMHTDTertiary amine, Armeen DMTD, Akzo hydrogenated tallowalkyl- NobelChemical dimethylamine** M2HT Tertiary amine, Armeen M2HT, Akzodihydrogenated Nobel Chemical tallowalkyl-methylamine *Mooney viscositymeasured at 125° C., ASTM D1646. **Hydrogenated tallow containssaturated 3.5% C₁₄, 0.5% C₁₅, 31% C₁₆, 1% C₁₇, 61% C₁₈ and unsaturated3% C₁₈ (⅔ of the alkyl group is C₁₈)

TABLE 2 Viscosity values of BIMS with low and high Mooney values. ShearRate (l/s) Viscosity* of BIMS 2 Viscosity of BIMS 3 100 1274 1468 500378 383 1000 200 197 1500 136 133 *Measured at 220° C. using a capillaryrheometer. Values are in Pa-s.

TABLE 3 Viscosity values of DM16D-modified BIMS 2 at 220° C. in Pa-s.Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv. 0.25equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 DM16D DM16D DM16D DM16D 1001274 1673 1649 3304 2910 500 378 426 426 981 916 1000 200 230 239 571505 1500 136 152 171 416 361

TABLE 4 Thermal stability of DM16D-modified RIMS 2 at 1 s⁻¹ shear ratemeasured using an oscillatory rheometer. Temperatures were ramped upfrom 100° C. to 250° C. and down to 100° C. and back up to 250° C. at 5°C./min. Viscosity* of BIMS with Viscosity of RIMS with Temperature (°C.) 0.25 equiv. DM16D 1.0 equiv. DM16D 250 (first down) 19770 124000 200(first down) 21089 124000 150 (first down) 26387 117000 100 (first down)39526 111000 150 (second up) 25862 111000 200 (second up) 21600 125000250 (second up) 18909 131000 *values in Pa · s.

TABLE 5 Viscosity values of DMHTD-modified BIMS 2 at 220° C. in Pa-s.Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv. 0.25equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 DMHTD DMHTD DMHTD DMHTD 1001274 1892 1916 3209 . . .* 500 378 517 594 861 963 1000 200 317 315 472499 1500 136 . . .* 211 312 339 *did not measure

TABLE 6 Viscosity values of M2HT-modified BIMS 2 at 220° C. in Pa-s.Shear BIMS with BIMS with BIMS with BIMS with Rate 0.1 equiv. 0.25equiv. 0.5 equiv. 1.0 equiv. (l/s) BIMS 2 M2HT M2HT M2HT M2HT 100 1274N/C* 1997 2372 2227 500 378 N/C 496 645 679 1000 200 N/C 263 368 3881500 136 N/C 182 276 275 *N/C- No change from the pure BIMS 2.

TABLE 7 BIMS dispersion size Blend Dispersion Size (micron) Control 2.08Modified BIMS 1.42

TABLE 8 Copolymer blend with Polypropylene Component/property (parts byweight) Control (a) (b) (c) PP 4772 18 18 18 18 BIMS 1 27 27 27 27Armeen DM16D — 1.5 1.0 0.5 Oil 4.5 4.5 4.5 4.5 Irganox 1076 0.09 0.090.09 0.09 MgO (Maglite D) 0.135 0.135 0.135 0.135 100% Modulus, psi 570950 830 720 200% Modulus, psi — 1170 1100 960 Strain at break, % 130 500470 410 Max. Stress near Break, psi 580 1800 1600 1400 TensileToughness, psi 670 6240 2440 1850

TABLE 9 Copolymer blend with Polypropylene Component/property (parts byweight) Control Control (d) (e) PP 4772 13.5 13.5 13.5 13.5 BIMS 1 31.531.5 31.5 31.5 Armeen DM16D — — 1.16 1.16 Oil 4.5 9.0 4.5 9.0 Irganox1076 0.09 0.09 0.09 0.09 MgO (Maglite D) 0.135 0.135 0.135 0.135 100%Modulus, psi 100 75 440 280 200% Modulus, psi 70 24 660 460 Strain atBreak, % 570 350 640 680 Max. Stress near Break, psi 8 3 1380 1100Tensile Toughness, psi 270 120 5470 4430

TABLE 10 Copolymer blend with Polypropylene Component/property (parts byweight) Control Control Control (f) (g) (e) PP 4772 13.5 13.5 13.5 13.513.5 13.5 BIMS 2 31.5 31.5 31.5 31.5 31.5 31.5 Armeen DM16D — — — 1.161.16 1.16 Oil 4.5 9.0 13.5 4.5 9.0 13.5 Irganox 1076 0.09 0.09 0.09 0.090.09 0.09 MgO (Maglite D) 0.135 0.135 0.135 0.135 0.135 0.135 100%Modulus, psi 180 130 36 550 320 440 200% Modulus, psi 160 100 26 830 510630 Strain at Break, % 650 920 1280 710 710 600 Max. Stress near 35 30.2 1900 1230 1200 Break, psi Tensile Toughness, psi 730 450 110 81005200 4500

We claim:
 1. A thermoplastic composition comprising at least oneisoolefin copolymer comprising a halomethylstyrene derived unit mixedwith at least one hindered amine or phosphine compound having therespective structure R₁ R₂ R₃ N or R₁ R₂ R₃ P wherein R₁ is H or C₁ toC₆ alkyl, R₂ is C₁ to C₃₀ alkyl and R₃ is C₄ to C₃₀ alkyl and furtherwherein R₃ is a higher alkyl than R₁; and a thermoplastic.
 2. Thecomposition of claim 1, wherein the isoolefin copolymer and the amine orphosphine are mixed prior to addition of the thermoplastic, the mixingaccomplished at a temperature above the melting point of said hinderedamine or phosphine compound.
 3. The composition of claim 1, wherein thethermoplastic comprises from 10 to 90 wt % of the composition.
 4. Thecomposition of claim 1, wherein the thermoplastic is selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof.
 5. The composition of claim 1, whereincuratives are substantially absent.
 6. The composition of claim 1,wherein R₃ is C₁₀ to C₂₀ alkyl.
 7. The composition of claim 1, whereinsaid hindered compound is a tertiary amine and wherein R₃ is C₁₀ to C₂₀alkyl.
 8. The composition of claim 3, wherein R₁ and R₂ are each methyl.9. The composition of claim 1, containing from 0.05 to 2 moles of amineor phosphine per halogen.
 10. The composition of claim 1, wherein theisoolefin copolymer is a halogenatedpoly(isobutylene-co-p-methylstyrene).
 11. The composition of claim 7,wherein the vulcanized thermoplastic composition has a strain at breakvalue of greater than 200%.
 12. The composition of claim 7, wherein thevulcanized thermoplastic composition has a tensile toughness of greaterthan 1000 psi.
 13. A process for preparing a thermoplastic compositioncomprising mixing: at least one isoolefin copolymer comprising ahalomethylstyrene derived unit; at least one hindered amine or phosphinecompound having the respective structure R₁ R₂ R₃ N or R₁ R₂ R₃ Pwherein R₁ is H or C₁ to C₆ alkyl, R₂ is C₁ to C₃₀ alkyl, and R₃ is C₄to C₃₀ alkyl and further wherein R₃ is a higher alkyl than R₁; and athermoplastic, and recovering a thermoplastic composition.
 14. Theprocess of claim 13, wherein the mixing takes place at a temperature offrom 150° C. to 240° C.
 15. The process of claim 13, wherein thethermoplastic comprises from 10 to 90 wt % of the composition.
 16. Theprocess of claim 13, wherein the thermoplastic is selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof.
 17. The process of claim 13, whereinsaid thermoplastic polymer is polypropylene or nylon.
 18. The process ofclaim 13, wherein R₃ is C₁₀ to C₂₀ alkyl.
 19. The process of claim 13,wherein curatives are substantially absent.
 20. The process of claim 13,wherein R₁ and R₂ are each methyl.
 21. The process of claim 13, whereinsaid copolymer contains from 0.05 to 2 moles of amine or phosphine perhalogen.
 22. The process of claim 13, wherein a solvent is substantiallyabsent during mixing.
 23. The process of claim 13, wherein the isoolefincopolymer is a halogenated poly(isobutylene-co-p-methylstyrene).
 24. Aprocess for preparing a thermoplastic composition comprising firstmixing at least one isoolefin copolymer comprising a halomethylstyrenederived unit: at least one hindered amine or phosphine compound havingthe respective structure R₁ R₂ R₃ N or R₁ R₂ R₃ P wherein R₁ is H or C₁C₆ alkyl, R₂ is C₁ to C₃₀ alkyl, and R₃ is C₄ to C₃₀ alkyl and furtherwherein R₃ is a higher alkyl than R₁; recovering an amine orphosphine/copolymer composition; mixing the amine or phosphine/copolymercomposition and a thermoplastic; and recovering a thermoplasticcomposition.
 25. The process of claim 24, wherein the mixing isaccomplished at a temperature above the melting point of said hinderedamine or phosphine compound.
 26. The process of claim 24, wherein thethermoplastic comprises from 10 to 90 wt % of the composition.
 27. Theprocess of claim 25, wherein the thermoplastic is selected frompolyolefins, polyamides, polyimides, polyesters, polycarbonates,polysulfones, polylactones, polyacetals, acrylonitrile/butadiene/styrenecopolymer resins, polyphenylene oxides, ethylene-carbon monoxidecopolymers, polyphenylene sulfides, polystyrene, styrene/acrylonitrilecopolymer resins, styrene/maleic anhydride copolymer resins, aromaticpolyketones and mixtures thereof.
 28. The process of claim 24, whereinsaid thermoplastic polymer is polypropylene or nylon.
 29. Thecomposition of claim 24, wherein the viscosity value of the amine orphosphine/copolymer composition is from 1300 to 6000 Pa·s at 220° C. and100 1/s shear rate (as measured by ASTM D1646).
 30. The process of claim24, wherein the viscosity value of the amine or phosphine/copolymercomposition is greater than 200 Pa·s at 220° C. and 1000 1/s shear rate(as measured by ASTM D1646).
 31. The process of claim 24, wherein asolvent is substantially absent during mixing.
 32. The process of claim24, wherein curatives are substantially absent.